Manufacture of soap



March 26., 1946.

l.. SENDER x-:TAL

MANUFAGTURE OF SOAP 'Filed Nov. 25, 1943 WUVRW QQQDWW Ok l TOW @nu ww Patented Mar. 1946 yUNITED l STATES PATENT oFFlcE l y assaut Leopold Sender, Baltimore, Md., and Leo D, Jones, Philadelphia, Pa., assignors to The Shar-plea Corporation, Philadelphia, Pa., a corporation The present invention pertains to manufacture of soap by a continuous process. It is an improvement in the prior processes described in the patents to Scott 2,300,749 and 2,300,750. In the processes of the above-mentioned Scott patents,

while maintaining the reagent mixture at an elevated temperature. From the mixing apparatus in which the saponication is accomplished, the resulting soap-containing mass is passed through a centrifugal separator which removes spent saponifying reagent from the formed soap, l5

which has previously been grained by the addition of salt or equivalent reagent.

In practice of processes such as those described in the Scott patents, -dilllculty has sometimes obtain a higher degree of saponiilcation of the fat than would otherwise -be possible. A feature of thel present invention-lies in the fact that care is exercised to obtain saponiflcation of the fatty acid content (both free and combined) o1 the fat under treatment to an extent providing a mixture in each of the respective -compartments of the mixer, in which the available fatty acid has been saponilled to an extent in excess of 85% or below r10%. As av further feature, a compartment of the mixer upstream from the furthest downstream compartment contains -a mixture of which the fatty acid content of the available iat has been saponied to an extent in excess of 85%. As a still further feature, a com partment of the mixer downstream from the compartment in which the saponiflcation has proceeded to an extent in excess of 85% is provided with a connection through which a furbeen encountered due to formation of emulsions ther quantity of fat is fed thereto for saponiicaof soap in spent reagent which are extremely diflcult to separate. As a result of this difficulty, it is necessary to provide centrifugal equipment of capacity in excess of that 4which would be retion. This last-mentioned feature, when combined with the featuresof saponiflcation in excess of 85% in one of the earlier compartments of the mixer, renders it possible for lthe operator quired, if such difficulties were not encountered. to obtain effective utilization of the aqueous sa- The reason for necessity oiVs'uch excess centrifugal capacity is that, in cases of centrifugal treatment of mixtures which are difficult to separate into soap and aqueous phases respectively, suicient centrifugal capacity must be available to provide more prolonged centrifugation than would otherwise be necessary.

The present invention rests upon the discovery of an improved process by which the formation of dimcultly separable emulsions may be consistently avoided. As a result, the processes of the Scott patents, when modifled to include the features of the present invention. can be uniformly operated to obtain a saponilcation reaction mixture which can .be readily separated centrlfugally.

Inl the practical operation of a` process such as that described in either of the Scott patents discussed above, mixing apparatus is used which provides for progressive passage of the reaction mixture through a series of mixing compartments. These mixing compartments may be either separate compartments of a single large ponifying reagent in spite of the fact that an excess of this reagent may previously have been added in order to insure saponication in excess of 85% in an upstream compartment of the i mixer.

The above and other features of the invention will be more evident from a reading of the folr o it is continuously passed into confluence with an aqueous saponifying reagentwhich may be lye fromcontainer ii, the fat and reagent solutions being pumped into confluence in mixer .it

by Dumps i2 and i3, respectively, as described f 5 in the above-mentioned Scott patents. The fat may be pre-heated in heater I5 to bring it to a saponifying temperature before admixture with the lye. Brine may also be passed from con-A tainer 22 by pump 23 into coniluence with the p mixer sub-divided by1 bailles, or they may be 1n 50 fat and lye in mixer i4, in order to grain soap the form of a plurality of separate small mixers. In either case, the purpose of compartmentation is to insure a more thorough reaction of the fat with the saponifying reagent to cause thorough utilization of the saponifying reagent. and to the mixer i4 as discussed in the patent to Scott,l

formed by the saponifying reaction. Alternatively, such brine maybe mixed with the lyc before being passed to the mixer il, or brine may be passed to a subsequent compartment of drawing. the mixer comprises a plurality of mixing compartments. Figure 1 of the drawing illustrates the provision of four successive compartments, I6, I1, I9 and I9, Iof which the rst or upstream compartment I6 is of substantially larger capacity than the subsequent or downstream compartments. Each compartment may also be provided with a coil 20 for passage of a heat exchange fluid. Thus, a heating iiuid may bel passed through the coil 20 in the compartment I6, in order to bring the reaction mixture to a very high temperature to insure reaction of the fatty acid content to an extent above 85% in this compartment, and the downstream com partments I1, I8 and I9 may have cooling fluids passed through the coils of these compartments in order to cool the reaction mixture to a temperature sulciently low to permit-,centrifugation without vaporization of aqueous phase as it enters the centrifugal 2 I. f

As pointed out above, the applicants have discovered that, by maintaining an extent of saponiication of the fatty acid of the fat fed to the mixer I4 which is below l70% or above 85% in each mixing compartment, the operation of separation of the grained soap from the aqueous reagent solution may be greatly facilitated. The primary conditions aifecting the extent of saponification of the available fatty acid are the amount and strength of the saponifying reagent, the degree of heat applied to effect saponication and the time interval provided for such saponication. The extent of saponication in a given compartment may be increased by an increase in the value of any one of these four factors. In the practice of the invention as illustrated in Figure 1, the compartment I6 is made larger than succeeding compartments and additional heat is also applied to the reaction mixture in this compartment, in order to insure attainment of saponication in excess of 85% in that compartment.

While, as noted above, a primary feature of the present invention consists in attainment of saponication in excess of 85% in some compartment of the mixer upstream from the furthest downstream compartment thereof, this result of extensive saponiiication in an upstream compartment, and particularly in the rst compartment of the mixer, sometimes requires addition of a relatively high proportion of saponifying reagent to'fat. As a consequence of this fact, it is sometimes difficult to attain the object of saponication in excess of 85% in an upstream compartment of the mixer consistently with attainment of the desirable depletion of thesaponifying reagent. In accordance .with the present invention, a, further quantity of fatis `separately introduced into a compartment of the mixer downstream from the rst such compartment in which saponication to an extent in ex'v cess of 85% is attained, this additional quantity of fat servingy to utilize excess saponifying reagent whichvmay initially be introduced to inarcaica sure saponification in excess of 8.5% in a com-f partment in advance of that -into which the additional stream of 'fat is introduced.L By

introducing a separate ,quantity of fat in this manner, the desirable depletion ofthe reagentV is introduced, a mixture containing fat saponifat introduced through the by-pass line 26 and that through the main line 21 may be accomplished by valves/24 and 25, respectively. By

controlling these valves, it is possible for the operator to control the relative proportions of fat introduced'into the compartments I6 and I1, respectively, and thus to eiect a measure of control over saponiflcation in these respective compartments insuring maintenance of saponiiication conditions as described above.

The saponication reaction mixture from the furthest downstream compartment I9 is passed directly to centrifugal 2I, where it is separated into soap and aqueous reagent phases, respectively, as described in the Scott patents mentioned above. i

Figure 2 of the drawing illustrates a slight modification, by which a slightly diiferent control of the extent of saponication in the respective Amixing compartments is eiected Within the principles of the invention. As illustrated in thatv figure, fat, lye and brine from containers 30, `3I and 42, respectively, are passed by pumps 32, 33 and 43, respectively, to mixer 34, the fat being passed through a heater 35 if desired. The mixer 34 contains four mixing compartments, `as illustrated, the rst, third and fourth compartments,

36, 38 and 39 being smaller than the Ycompart sures sapom'iication therein to an extent above The compartment 36 being smaller,l and the degree of heat in this compartment being less, saponication may be controlled in compartment 36 to maintain it below 70%. Either heating or cooling iiuid may be introduced into the coils vof compartments 38 and 39, depending upon the degree of heat reached in compartment 31, it being important to provide a mixture for feed from compartment 39 to centrifugal 4I which will not flash into vapor upon introduction into that centrifugal. In the embodiment of VFigure 2, as in the embodiment of Figure 1,y

a separate quantity of fat is introduced into a compartment downstream from the compartment in which saponication in excess of 85% is first attained. As illustrated in Figure 2, a by-pass line 46 leads from a portion of line I1 connecting heater 35 with mixing compartment'` 36, and a part lof the fat is conducted directly throughthe line 46 to mixing compartment 38.

'The relative proportions of fat fed to 'compartments 36 and 3,8, respectively, are controlled by asoman i aon with Figure 1 is claimeain the patent to' valves I and u, lrespectively. It willbe seen that, in this embodiment as 'well as in the embodiment of. Figure 1, a degree of saponiilcation in each ofthe respective compartments of the mixer can be maintained below 70% or above 85%. the embodiment of Figure 2 being practiced by maintaining it below 70% in compartment 36 and above85% in compartments 31,438 and 39.

The invention has been described above as though it involvedv the first stage of the d,saponiflcation process. `It may, however, be employed in the second or other subsequent stage lof such a process. vThus, in practice of this invention in the second stage of a counter-current process. the fat-containing material fed from the container I0 or 30 is a mixture of fat and soap derived from the iirst stage of the process and containing a quantity of unsaponiiled available fatty acid (free and combined) vin excess of 30%, due to maintenance of the precautions discussed above in practice of the ilrst stage ofthe process to avoid saponiilcation in excess of 70%. In such case, the process would be conducted in such a manner that 'the' degree of saponiication of the original saponiilable fat was raised to an extent above 85% in the compartment I6 or the compartment 31 (depending upon whether the invention was' 'practiced in accordance with Figure 1 or Figure 2) and further fat would thereafter be added in a compartment subsequent to that in which saponiilcation was ilrst completed in excess of 85%, the other conditions of the invention also being maintained in the respective compartments as discussed above. The features of the invention as discussed above may be employed either in a single stage process or in a multi-stage process, and the process being preferably a multi-stage countercurrent operation. In the preferred practice of the invention, however, a continuous multi-stage counter-current process' is employed as described in the above-mentioned Scott patents.

In this application, we are claiming the combination of features of control of the extent of saponification yin the respective mixing compartments with the feature of addition of further fat in a compartment downstream from the compartment in which saponiilcation in excess of 85% is rst attained. In a co-pending application Serial No. 511,707, illed November 25, 1943, we are lclaiming broadly the feature of maintaining. the reaction mixtures in the various mixer compartments in a. suitable condition to avoid formation of diillcultly inseparable emulsions.

The feature of heating the fat and later cooling the reaction mixture discussed in connec- Scott, 2,348,855, of May 16, l

various modmcanons are possible within the scope of the invention, and we do not therefore wish to be limited except .by the scope of the following claims.

y l We claim:

1. In the manufacture of soap by continuous saponiilcation of fat, graining of the resulting soap and separation of grained soap from aqueous reagent solution by subsidence, the process comprising continuously passing a fat together with lye progressively through a succession of Ving in excess of 85%,

compartments at a saponifying temperature, maintaining saponifying conditions in the respective compartments adapted to produce a saponifled mixture in each compartment of which the proportion of the available fatty acid of the source of fat which has been saponied is outside of the range between 70% and 85% of said available fatty acid, said proportion of available fatty acid saponied in a compartment of the mixer atleast one compartment upstream from the furthest downstream compartment betity of' fat into a compartment of said mixer downstream from the compartment in which said 85% of fatty acid saponication has i'lrst been attained, and controlling the saponication conditions 'in the compartment in which said further quantity of fat has been introduced and in any compartments of said mixer downstream from said compartment of introduction to produce a saponiiied mixture in each o f said compartments of which the proportion of available fatty acid of the source of fat which has been saponiiled is above 85 and subjecting the resulting mixture to centrifugation and thereby l separating aqueous reagent from grained soap.A

2. A process as dened in claim 1, in which saponifying conditions in each of the respective compartments are maintained to produce a saponifled mixture in. each compartment of which the proportion of the available fatty acid of the source of fat which has been saponifled is above 85% of said available fatty acid.

5 tioned compartment.

3. A process as defined in claim 1, in which I' the saponication in the 'furthest upstream mixing compartment is: below the saponication in a compartment downstream from said mst-mentioned compartment is above and the further quantity of fat is introduced in a compartment downstream from said last-men- LEOPOLD SENDER. LEO D. JONES.

introducing a further quan- I 

